Corn is a major crop used as a human food source, an animal feed, and as a source of carbohydrate, oil, protein, and fiber. It is principally used as an energy source in animal feeds.
Most corn grain is handled as a commodity, since many of the industrial and animal feed requirements for corn can be met by common varieties of field corn which are widely grown and produced in volume. However, there exists at present a growing market for corn with special end-use properties which are not met by corn grain of standard composition.
More than 50% of the maize grain crop produced in the USA is used for animal feed animal (Perry (1988) Corn and Corn Improvement, eds. Sprague and Dudley (Madison, Wis.), pp. 941-963). Maize grain with elevated oil concentration has a higher caloric content compared with standard maize grain and is advantageous as a food source for animals. Feeding high-oil maize grain instead of maize grain with standard levels of oil concentration to swine and poultry has resulted in accelerated weight gain (Han et al. (1987) J. Poult. Sci. 66:103-111 and Gross et al. (1992) Proc. of the 47th Ann. Corn and Sorghum Res. Conference, pp. 82-92).
Oil as a major seed storage compound, also has significant economic value for food and industrial markets.
Thus, the development of high-oil germplasm is an objective of some maize breeding programs.
There are serious limitations to using mutagenesis to increase oil levels in grain. Screens will rarely uncover mutations that a) result in a dominant (“gain-of-function”) phenotype, b) are in genes that are essential for plant growth, and c) are in an enzyme that is not rate-limiting and that is encoded by more than one gene. In cases where desired phenotypes are available in mutant corn lines, their introgression into elite lines by traditional breeding techniques is slow and expensive.
Methods and compositions that improve the oil content of plants and provide for efficient methods of developing these plants are needed in the art.